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PubMed2006

Differential expression of transcriptional repressor snail gene at implantation site in mouse uterus.

The snail superfamily of zinc-finger transcription factors is involved in pronounced cell movements during both embryonic development and tumor progression. This study was to examine snail expression in mouse uterus during early pregnancy and its regulation under pseudopregnancy, delayed implantation, steroid hormone treatment, and artificial decidualization by in situ hybridization and immunohistochemistry. There was a low level of snail mRNA signal and immunostaining in mouse uteri on day 1-4 of pregnancy. When embryo implanted on day 5, both snail mRNA signal and immunostaining were strongly detected in the subluminal stroma immediately surrounding the implanting blastocyst, but not detected in the inter-implantation sites. Under delayed implantation, there was no detectable snail expression. After delayed implantation was terminated by estrogen treatment and embryo implanted, there was a strong level of snail mRNA and immunostaining in the subluminal stroma surrounding the implanting blastocyst, which was similar to that on day 5 of pregnancy. Furthermore, there was no detectable snail expression in mouse uterus on day 5 of pseudopregnancy. From day 6-8 of pregnancy, both snail mRNA signal and immunostaining were detected in the decidua. Our data suggest that snail may play an important role during mouse embryo implantation.

Animals↗

PubMed1991

Laminin-like immunoreactivity in the snail Helisoma: involvement of approximately 300 kD extracellular matrix protein in promoting outgrowth from identified neurons.

Polyclonal antibodies directed against laminin (LM), and against the A and B chains of reduced LM were used to identify antigenically related proteins in the extracellular matrix (ECM) of the snail Helisoma trivolvis. Immunofluorescence of snail central ganglionic rings using either the anti-LM or anti-B chain antibodies labeled the ECM within ganglionic sheaths as well as basal laminae surrounding the ganglia. Both the anti-LM and anti-B chain antibodies recognized a prominent, approximately 300-kD protein on immunoblots of a snail central ganglion preparation enriched in ECM components. The anti-A chain antibody failed to label any structures in sections of snail ganglia or to recognize any proteins on immunoblots of ganglionic ECM. A polyclonal antibody was raised against the approximately 300-kD snail protein. Immunofluorescence of snail ganglia with the anti- approximately 300-kD antibody gave a distribution of labeled structures comparable to that obtained with the anti-LM antibody. Immunofluorescent labeling of sections of snail muscle and salivary gland with the anti- approximately 300-kD antibody revealed a distribution of reactive protein characteristic of an ECM component. Probing immunoblots of ganglionic ECM with the anti- approximately 300-kD antibody revealed the recognition of the same approximately 300-kD protein as identified by the anti-LM antibodies. Media conditioned by Helisoma central ganglionic rings (CM) contains an unidentified neurite outgrowth promoting factor (NOPF). Immunoblots of CM probed with the anti-B chain and anti- approximately 300-kD antibodies reveal the recognition of a soluble approximately 300-kD protein similar to the approximately 300-kD protein identified in snail ECM. The ganglionic ECM preparation containing the approximately 300-kD protein supported outgrowth from cultured snail buccal neurons B5, and addition of anti- approximately 300-kD Fab fragments to CM abolished its outgrowth promoting activity. These results suggest that the approximately 300-kD ECM protein may be the NOPF in CM and/or functions in promoting neurite outgrowth.

Animals↗

PubMed2005

The transcriptional repressor SNAIL is overexpressed in human colon cancer.

Overexpression of the transcriptional repressor, SNAIL, has been implicated in the pathogenesis of a number of malignancies; however, there are no previous reports on the role of SNAIL in colorectal cancers (CRCs). We, therefore, evaluated human CRC specimens for the presence of the SNAIL protein. Immunohistochemical studies were performed using samples obtained from archived CRC paraffin blocks and a tissue array. Tissue sections were probed with a polyclonal antibody to human SNAIL and scored by a gastrointestinal pathologist. SNAIL was not detectable in uninvolved mucosa, but immunoreactivity was evident in 78% of tumors. SNAIL protein expression did not correlate with subsite location or gender, however, SNAIL-positive tumors had an older mean age (58.9 +/- 12.7 versus 49.8 +/- 127; P = 0.028). Furthermore, there was a trend that CRCs with metastatic ability more frequently overexpressed SNAIL (100 versus 65%; P = 0.11). In conclusion, we demonstrate, for the first time, that SNAIL is upregulated in human colon cancer, which potentially may have significance in control of metastasis and possibly serve as a target for chemopreventive agents.

Aging↗

PubMed2002

Is the cadmium uptake from soil important in bioaccumulation and toxic effects for snails?

To evaluate the contribution of digestive and epithelial transfer of Cd from soil to snail, Helix aspersa was exposed to an artificial substrate contaminated with 0,100,500, and 1000 microg Cd.g(-1) for 4 weeks under laboratory conditions. Two modes of exposure were used: (1) the snails were in direct contact with the substrate (DC) or (2) were separated from substrate with a perforated plate (no contact (NC)) which allowed ingestion of substrate but avoided epithelial contact. Cd concentrations in DC snails were twice as high as in NC snails. The bioaccumulation factors were 0.51+/-0.13 in DC snails and 0.26+/-0.04 in NC snails. Dose-dependent growth inhibition was noted in DC snails (500<EC(50)<1000 microg.g(-1) and EC(10) around 100 microg.g(-1)) while only slight effects were noted in NC snails. Internal Cd concentrations in DC and NC snails were linearly correlated with growth effect whatever the contamination route.

Animals↗

PubMed2003

Behavioral responses of sexually active mud snails: kariomones and pheromones.

We postulated that kariomones and pheromones function to organize egg capsule deposition and breeding aggregations of mud snails (Ilyanassa obsoleta). Sexually active male and female mud snails were exposed to water-born odors from juvenile snails, nonaggregated female snails, oysters, egg capsule depositing snails, sexually active males, sexually active females, and copulating snails and tested for a follow response using a ring assay. Neither sex responded to juvenile odor or to odor of sexually inactive females. Snails turned and followed water born odors from oysters, when tested with the odors of sexually active males, sexually active females, and copulating pairs, we found sex-specific differences in responses. Sexually active females followed the odor of sexually active males and ignored sexually active female odor. Sexually active males followed the odor of sexually active females and ignored sexually active male odor. Both sexes followed the odor of copulating pairs and egg capsule depositing snails. Snail activities in breeding aggregations are organized by at least three pheromones and one kariomone, and reflect the multifunctionality of the aggregations.

Animals↗

PubMed2002

Snail induction of epithelial to mesenchymal transition in tumor cells is accompanied by MUC1 repression and ZEB1 expression.

E-cadherin protein plays a key role in the establishment and maintenance of adherent junctions. Recent evidence implicates the transcription factor Snail in the blockage of E-cadherin expression in fibroblasts and some epithelial tumor cells through direct binding to three E-boxes in the E-cadherin promoter. Transfection of Snail into epithelial cells leads to a more fibroblastic phenotype. Cells expressing Snail presented a scattered flattened phenotype with low intercellular contacts. Other epithelial markers like Cytokeratin 18 or MUC1 were also repressed. The effects of Snail on MUC1 transcription were mediated by two E-boxes present in the proximal promoter. Snail also induced expression of the mesenchymal markers fibronectin and LEF1 and the transcription repressor ZEB1. ZEB1 and Snail had a similar pattern of expression in epithelial cell lines, and both were induced by overexpression of ILK1, a kinase that causes the loss of E-cadherin and the acquisition of a fibroblastic phenotype. Snail overexpression in several cell lines raised ZEB1 RNA levels and increased the activity of ZEB1 promoter. ZEB1 could also repress E-cadherin and MUC1 promoters but less strongly than Snail. However, since ZEB1 expression persisted after Snail was down-regulated, ZEB1 may regulate epithelial genes in several tumor cell lines.

Animals↗

PubMed2003

Mouse Snail family transcription repressors regulate chondrocyte, extracellular matrix, type II collagen, and aggrecan.

Snail family genes are conserved among species during evolution and encode transcription factors expressed at different stages of development in different tissues. These genes are involved in a broad spectrum of biological functions: cell differentiation, cell motility, cell cycle regulation, and apoptosis. However, little is known about the target genes involved in these functions. Here we show that mouse Snail family members, Snail (Sna) and Slug (Slugh), are involved in chondrocyte differentiation by controlling the expression of type II collagen (Col2a1) and aggrecan. In situ hybridization analysis of developing mouse limb demonstrated that Snail and Slug mRNAs were highly expressed in hypertrophic chondrocytes. Inversely, the expression of collagen type II mRNA disappeared during hypertrophic differentiation. Snail and Slug mRNA expression was down-regulated during differentiation of the mouse chondrogenic cell line ATDC5 and overexpression of exogenous Snail or Slug in ATDC5 cells inhibited expression of collagen type II and aggrecan mRNA. Reporter analysis revealed Snail and Slug suppressed the promoter activity of Col2a1, and the E-boxes in the promoter region were the responsible element. Gel shift assay demonstrated the binding of Snail to the E-box. Because type II collagen and aggrecan are major functional components of extracellular matrix in cartilage, these results suggest an important role for Snail-related transcription repressors during chondrocyte differentiation.

Aggrecans↗

PubMed1998

Cross-reactivity between terrestrial snails (Helix species) and house-dust mite (Dermatophagoides pteronyssinus). II. In vitro study.

Epidemiologic and in vitro data have shown that the association of house-dust mite (HDM) allergy and snail allergy in the same patients was due to cross-reactivity between HDM and snail allergenic components. However, the cross-reacting allergen(s) have not yet been identified. In vitro reactivity of seven patients' sera to the various extracts and hemolymph of four different Helix snail species was analyzed by IgE detection and immunodots and Western blots. Cross-reactivity between snails and Dermatophagoides pteronyssinus was assessed by immunodot and ELISA inhibition in two patients. Heterologous inhibition of the snail immunodot and ELISA was observed in one serum. Western blotting showed a specific binding on all four snail species extracts; molecular weights of snail allergens ranged from < 21 to 200 kDa. Marked individual differences were observed in the seven sera under study; most sera demonstrated IgE recognition of multiple bands, illustrating that no single allergen is responsible for cross-reactivity between snail and mite. These results confirm that cross-reactivity exists between snails of the Helix genus and HDM. This cross-reactivity, involving more than a single allergen, may be of clinical significance in atopic patients allergic to D. pteronyssinus. The identity of the cross-reacting allergens remains to be determined. Potential candidates include the thermostable minor allergens of D. pteronyssinus, tropomyosin and hemocyanin.

Animals↗

PubMed2004

The Helix aspersa (brown garden snail) allergen repertoire.

BACKGROUND: Ingestion of snails can induce strong asthmatic or anaphylactic responses, mainly in house-dust-mite-sensitized patients. The aim of this study was to identify the Helix aspersa (Hel a), Theba pisana (The p) and Otala lactea (Ota l) allergens and the extent of their cross-reactivity with the Dermatophagoides pteronyssinus (Der p) mite. PATIENTS AND METHODS: In 60 atopic patients, skin prick tests (SPT) to snail and D. pteronyssinus, total and specific IgE, specific IgE immunoblots, RAST and immunoblot inhibition assays were performed. RESULTS: Mean total IgE was >1,000 kU/l. Mean specific IgE (class 6 for Der p and class 2 for Hel a) SPT were positive in 44 patients for snail and in 56 for mite. Isoelectric focusing (IEF) and SDS-PAGE followed by immunoblotting of H. aspersa extract enabled the identification of 27 and 20 allergens, respectively. Myosin heavy chains from snails (molecular weight >208 kDa) disclosed two major allergens. Hel a and Der p RAST were strongly inhibited by their homologous extracts, with Hel a RAST being inhibited by the Der p extract to a much greater extent (72.6%) than the inverse (5.6%). A complete inhibition of the immunoblots by their homologous extract was obtained. However, Hel a extract did not inhibit Der p IEF separated recognition. On the other hand, mite extract extensively inhibited snail immunoblots from both IEF and SDS-PAGE separations. Immune detection on chicken, pig, rabbit, cow and horse myosins did not reveal any IgE cross recognition with snail. CONCLUSIONS: In most cases of snail allergy, mite appeared to be the sensitizing agent. Nevertheless, snails may also be able to induce sensitization by themselves. This hypothesis is supported by the finding of specific IgE to Hel a in 2 patients who did not show specific IgE to Der p, and one of them was suffering from asthma after snail ingestion.

Adolescent↗

PubMed2005

Upregulation of MMP-9 in MDCK epithelial cell line in response to expression of the Snail transcription factor.

Overexpression of the transcription factor Snail in epithelial MDCK cells promotes the epithelial-mesenchymal transition (EMT) and the acquisition of an invasive phenotype. We report here that the expression of Snail is associated with an increase in the promoter activity and expression of the matrix metalloproteinase MMP-9. The effect of Snail silencing on MMP-9 expression corroborates this finding. Induced transcription of MMP-9 by Snail is driven by a mechanism dependent on the MAPK and phosphoinositide 3-kinase (PI3K) signalling pathways. Although other regions of the promoter were required for a complete stimulation by Snail, a minimal fragment (nucleotides -97 to +114) produces a response following an increased phosphorylation of Sp-1 and either Sp-1 or Ets-1 binding to the GC-box elements contained in this region. The expression of a dominant negative form of MEK decreased these complexes. A moderate increase in the binding of the nuclear factor kappaB (NFkappaB) to the upstream region (nucleotide -562) of the MMP-9 promoter was also observed in Snail-expressing cells. Interestingly, oncogenic H-Ras (RasV12) synergistically co-operates with Snail in the induction of MMP-9 transcription and expression. Altogether, these results indicate that MMP-9 transcription is activated in response to Snail expression and that it might explain, at least in part, the invasive properties of the Snail-expressing cells.

Animals↗

PubMed2003

The biocide tributyltin reduces the accumulation of testosterone as fatty acid esters in the mud snail (Ilyanassa obsoleta).

Imposex, the development of male sex characteristics by female gonochoristic snails, has been documented globally and is causally associated with exposure to the ubiquitous environmental contaminant tributyltin (TBT). Elevated testosterone levels in snails also are associated with TBT, and direct exposure to testosterone has been shown to cause imposex. We discovered previously that the mud snail (Ilyanassa obsoleta)biotransforms and retains excess testosterone primarily as fatty acid esters. The purpose of this study was to determine whether TBT interferes with the esterification of testosterone, resulting in the elevated free (unesterified) testosterone levels associated with imposex. Exposure of snails to environmentally relevant concentrations of TBT (> or = 1.0 ng/L as tin) significantly increased the incidence of imposex. Total (free + esterified) testosterone levels in snails were not altered by TBT; however, free testosterone levels increased with increasing exposure concentration of TBT. TBT-exposed snails were given [14C]]testosterone to measure the production of [14C]testosterone-fatty acid esters. The production of testosterone-fatty acid esters decreased with increasing exposure concentration of TBT. These results indicate that TBT elevates free testosterone levels in snails by decreasing the production or retention of testosterone-fatty acid esters. These findings were confirmed among field-sampled snails where individuals collected from a high-tin-affected site exhibited a greater incidence of imposex, higher free testosterone levels, and lower testosterone-fatty acid ester levels when compared with individuals sampled from a low-tin-affected site. Decreased testosterone-fatty acid esterification among TBT-treated snails was not caused by direct inhibition of the acyl coenzyme A:testosterone acyltransferase (ATAT) enzyme responsible for testosterone esterification, nor by suppressed ATAT protein expression. The target of TBT may be a co-contributor to the testosterone fatty esterification process or a factor in the enhanced hydrolysis of the testosterone-fatty acid pool.

Animals↗

PubMed2000

Evaluation of different means of control of snail intermediate host of Schistosoma mansoni.

Four water courses having the same conditions and snail density were chosen for this study. All methods were applied simultaneously in April. Snails were collected monthly to evaluate the malacological effect. A single application of 100 ppm dried A. maritima decreased the snail density significantly within one month. Snail density was maintained very low until the end of the year. Fresh Azolla pinnata applied in a dose of 280 ppm lowered snail density to a level intermediate between Ambrosia maritima and Bayluscide. Snail population began to build 5 months later. Bayluscide applied once at a dose of 1 ppm lowered significantly the snail density. This lowering was maintained for 4 months after which snails began to build up and remained high until the end of the study period. Clearing of vegetations was followed by abrupt lowering of snail density which was maintained for a period longer than that following Bayluscide and Azolla.

Animals↗

PubMed2002

[Observation on moving patterns of Oncomelania snails in rivers and canals].

OBJECTIVE: To understand the moving patterns of Oncomelania snails, intermediate host of S. japonicum, in the water bodies. METHODS: Based on the biological features of the snails, methods and techniques in relation to hydraulics and silt engineering were adopted to investigate the active scrawl ability and passive movement of the snails. RESULTS AND CONCLUSION: The scrawl speed of the snails themselves was very low, 2.45 mm per minute only. The active movement in the water current was therefore almost negligible. The major moving patterns of the snails in rivers and canals were that: 1. Snails adsorbed on different kinds of carriers drifted on the water. 2. Snails suspended on the water and drifted with the current, these were the young snails under 7 weeks of age. Adult snail showed a strong ability of adhesion, 12 times higher than its body weight.

Animals↗

PubMed1992

[Study on the effect of bromoacetamide upon the development of snail eggs].

This paper deals with the influence of bromoacetamide on the development of snail eggs, its effect on inducing diapause of snail eggs at different developmental stages (blastula, gastrula, trochophore and veliger) both at different concentrations of bromoacetamide at the same time and at same concentration at different times. Besides, the oviposition of the snails and the eggs within snails have also been studied. The results are as follows: 1. When the snail eggs were immersed in bromoacetamide at concentrations of 0.034ppm-0.067ppm, deformation of snail eggs appeared from unicellular to gastrula stages, but it was not observed after the trochophore-veliger stages. When the eggs at different stages were separately immersed in bromoacetamide, they were all found deformed. The molluscicidal concentration for inducing deformation of eggs was higher at the trochophore-veliger and metamophotic stages than that at the blastula and gastrula stages (Figs. 1-5). 2. After immersed in bromoacetamide solution, the development of the snail eggs were obviously retarded. The effects varied with different concentrations. Within the same exposure time, the higher the bromoacetamide concentration, the higher the diapause rate. 3. The longer the immersion time, the lower concentration was needed to delay the development and the lower hatching rate was for the eggs at the same or different stages. 4. After treatment with bromoacetamide, the average number of eggs laid by a female snail was reduced. 5. By using 3H-labeled bromoacetamide, it was found that the radioactivity of 3H-labeled bromoacetamide per hundred snail eggs was raised along with the increasing of the molluscicide concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetamides↗

PubMed2003

[Ecological surveillance on breeding ground for Oncomelania hupensis snails in the areas prevalent with islet-type schistosomiasis using remote sensing technology].

OBJECTIVE: To probe rational indices suitable for ecological surveillance on breeding ground for Oncomelania hupensis snails in areas prevalent with islet-type schisitosomiasis using remote sensing technology. METHODS: Three adjacent islets, prevalent with islet-type schistosomiasis, along the Yangtze River within the boundaries of Dongzhi County, Anhui Province were selected as study field for remote sensing analysis. Multi-spectral data were composed and non-supervisedly classified in computer with Idisi software for remote sensing analysis. Values of the normalized difference vegetation index (NDVI), green vegetation index (GVI), bright index (BI), which reflect the greenness and brightness of landscape, were also calculated. Finally, all the results were comprehensively analyzed, combined with data from the field investigation. RESULTS: NDVI, GVI and BI could depict characteristics of the landscape quantitatively. Values of NDVI, BI and GVI were varied in different types of landscapes, and 95% confidence interval of these values suitable for breeding of snails was 0.0522 approximately 0.3566, 2.4162 approximately 28.2672 and 29.3404 approximately 40.3135, respectively. Classification of NDVI showed that type 5 anf type 6 were main breeding ground for snails, and type 4 with values of NDVI from 0 to 0.1 was potential areas for snail propagation. Classification of GVI showed that types 5, 6 and 7 were main breeding ground for snails, and also type 4 with values of GVI from 2 to 10 was potential areas for snail propagation. Both NDVI and GVI showed type 2 and type 3 were temporarily not suitable for snail breeding. CONCLUSION: Index figures of NDVI and GVI re-formed by reasonable classification could reflect not only breeding ground for snails and range of the areas for snail propagation in islets, but also their evolving rules, i.e., status of new marshland formation and vegetation growth.

Animals↗

PubMed2005

The zinc-finger transcription factor Snail downregulates proliferating cell nuclear antigen expression in colorectal carcinoma cells.

The Snail family of zinc-finger protein is a transcription repressor that is involved in the development of vertebrate and invertebrate embryos as well as in tumor progression. This family leads to broad biological functions such as cell differentiation, cell motility, cell cycle regulation and apoptosis. However, the target genes of Snail remain little known. In this study, we found several potential Snail binding sequences in the 5'-flanking region of human PCNA gene. Cotransfection experiments showed that Snail reduces human PCNA gene promoter activity in colorectal carcinoma cell lines, HCT116 and Colo320HSR. Snail-reduced PCNA expression was detected in immunoblotting and immunochemistry. In BrdU incorporation experiment, Snail inhibited the BrdU incorporation. Electrophoretic mobility shift assays showed that Snail can bind to the potential Snail recognition sites in the human PCNA promoter. Taken together, our results suggest that Snail may have an inhibitory effect on cell proliferation through down-regulation of PCNA expression as a novel target.

5' Flanking Region↗

PubMed1990

Humoral response of the snail Biomphalaria glabrata to trematode infection: observations on a circulating hemagglutinin.

The hemolymph of invertebrates often contains molecules that agglutinate vertebrate erythrocytes and that may function as humoral mediators of "non-self" recognition. The objectives of this study were to 1) determine if exposure of M line or 10-R2 strain Biomphalaria glabrata snails to infection with the trematodes Echinostoma paraensei and Schistosoma mansoni could increase agglutinating activity in snail hemolymph, and 2) identify particular hemolymph molecules with such activity. In some host-parasite combinations, such as juvenile M line snails and E. paraensei, infection provoked significant elevations in titer from as early as 2 days postinfection (dpi) through 15 dpi. In other combinations, as with 10-R2 snails and E. paraensei or S. mansoni, host responses were comparatively modest, yet still measurable. In general, E. paraensei and S. mansoni elicited different responses from the same host strain, and M line and 10-R2 snails responded differently to the same parasite. Further study of the response of juvenile M line snails to E. paraensei indicated that hemolymph agglutinating activity could be inhibited by several monosaccharides (including L-fucose) and by EDTA and EGTA. An affinity column containing L-fucose agarose beads was used to purify molecules with agglutinating activity from the hemolymph of such snails. The fraction eluted from the column by 0.2 M L-fucose was shown by SDS-PAGE to contain a broad band of 80-120 kD and, less consistently, a 200 kD band. Following extensive dialysis to remove L-fucose, this fraction had agglutinating activity. As a previous study has shown that the hemolymph of E. paraensei-infected snails contains significantly increased quantities of 80-120 kD polypeptides, it is concluded that polypeptides in this size range are responsible, at least in part, for the increased hemolymph agglutination activity in such snails.

Animals↗

PubMed1994

Schistosoma mansoni: relationship between low fecundity and reduced susceptibility to parasite infection in the snail Biomphalaria glabrata.

Biomphalaria glabrata snails which were not susceptible as juveniles to infection by Schistosoma mansoni were selectively bred (by self-fertilization) from the highly susceptible NMRI laboratory snail stock. The susceptibility rate among juvenile snails derived from interbreeding NMRI parents was initially 85-95%, but after several generations of selection, less than 5% of exposed snails became infected by the parasite. Selection for low susceptibility also resulted in a large proportion of snails that displayed low fecundity and produced abnormal egg masses. Individual adult snails which were isolated from an interbreeding population of nonselected NMRI snails usually produced well-developed egg masses each containing 15-30 embryos. However, when juvenile snails from this same population were reared in isolation and not allowed to cross-fertilize, many displayed a pattern of low fecundity and abnormal egg production similar to that observed in the selected low susceptible line. Furthermore, it was found that many of the isolated snails which exhibited low egg production were also not susceptible to parasitic infection.

Animals↗